fix: show scrollbars only when an inner area overflows

assets/styles/app.css

@@ -32,3 +32,15 @@
         cursor: pointer;
     }
 }
+
+/*
+ * Thin scrollbars without a track for inner scrolling areas. The page scrollbar takes its
+ * style from <html>, which body * leaves out. Firefox and Chrome/Edge 121+ honour these;
+ * Safari keeps its own overlay scrollbars.
+ */
+@layer base {
+    body * {
+        scrollbar-width: thin;
+        scrollbar-color: var(--color-gray-300) transparent;
+    }
+}